Hi,
I would like to use Facebook login in my phalcon project. Do you guys have any step by step guide on any tutorials that can do so?
The best facebook login tutorials are the ones provided by Facebook itself. You won't find any other way to integrate them with your project since Facebook provide just one way and is through their api.
https://developers.facebook.com/docs/php/gettingstarted/4.0.0
https://github.com/facebook/facebook-php-sdk-v4
If it helps with anything you can take a look at my implementation, but is exactly the same stuff as the fb docs
https://github.com/magnxpyr/cms/blob/master/app/engine/Plugins/Connectors/FacebookConnector.php
https://github.com/magnxpyr/cms/blob/master/app/engine/Plugins/Auth.php#L160